


Rim of the Past

by Writingfish (idraax)



Category: Big Hero 6 (2014)
Genre: Alternate Universe - Pacific Rim Fusion, Gen, Podfic Welcome, Remixes welcome, Time Travel, You can do whatever you want with this story as long as you don't steal credit
Language: English
Status: In-Progress
Published: 2014-12-04
Updated: 2014-12-13
Packaged: 2018-02-28 03:39:50
Rating: Not Rated
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 6,418
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2717501
Author URL: https://archiveofourown.org/users/idraax/pseuds/Writingfish
Summary: <blockquote class="userstuff">
              <p>In which Hiro winds up in the past after fighting the Kaiju.</p>
            </blockquote>





	1. Prologue

**Author's Note:**

> Beta read/edited by [ cometotheberkside](http://cometotheberkside.tumblr.com/) and [ ruralhypsteria](http://ruralhypsteria.tumblr.com/)

**5:55 p.m, San Fransokyo Coastline, January 12, 2025**

San Fransokyo's coast was silent and empty except for two figures on the beach near the golden bridge.

"I do not like this plan," Baymax said as Hiro stared out at the calm, dark water.

"I'm the only one left," he murmered, mostly to himself.

Next to him was a missile, a metallic grey that nearly blended in with the twisted metal around it. He shuffled his feet, careful to avoid the shattered glass, that littered the beach in visible fragments.

"You know what to do?" he asked, turning to look at Baymax and memorizing the way he looked in the grey light.

Baymax blinked and Hiro knew he understood. He picked up the missile, strapping it to his back before moving to hug Baymax.

They stayed that way for a long time, Baymax recording every heartbeat, every breath and Hiro searing the texture of Baymax's vinyl into his brain.

Eventually, they had to separate and they did so reluctantly. Hiro took one last long look at Baymax before taking a deep breath and activating his boots and helmet. Baymax was looking at him with his customary expression, but Hiro could feel the displeasure radiating off of him.

"You have to get everyone out of range," he repeated, with a hint of desperation in his voice,  and Baymax nodded.

"I must voice my objection to this plan again. You are my patient and I cannot let you come to harm."

Hiro smiled sadly and reached out to pat him gently on the arm.

"I know you don’t, buddy. But I have to."

The weight of the weapon on his back grew heavier with each passing moment, their last hope pressing down on him, and Hiro knew he had to leave. 

_This has to work._

He flew into the air, resisting the urge to look back at the lonely beach and the ruined city beyond. The suit around him felt like a cage and he opened the helmet to take one last gasp of fresh air before he hit the water with a large splash.

It was dark inside the ocean and the water churned as the Kaiju rose. There were faint, distorted flashes of light showing through the water and it rippled and rose as buildings fell near the coast.

He dodged debris as he swam deeper and deeper into the ocean, to where the rift was approximated to be. There was too much disturbance from the rift to get an accurate picture of where and how enormous it was, but they had approximated it to be about 50 miles downward and outward of the city.  
  
Eventually, he reached it, swimming through the grey water and dodging the looming beasts that took lazy swipes at him thinking he was some sort of large fish.

He swallowed, a hurried intake of air, when he reached the edge of the rift, unstrapping the missile on his back and holding it out in front of him.

He let it out quickly and dove into the rift.

The rift was a swirl of dark blues and greens, empty and quiet. It was nothing like the portal he had dived through to find Abigail. He fell through it fast enough that he had to scramble to activate the missile, when his suit let out an alarm that nearly deafened him, before letting it fly through the other opening and into the other side.

The explosion blew him backwards and the heat and fire stripped his armor and chewed at his skin.

_I’ll see you soon Tadashi,_ he thought before the rift blurred and he dropped into the dark.

**San Fransokyo**

He fell, landing on the concrete with a harsh thump and skidding a few feet into the nearest lamppost.

"Ow," he groaned, touching his cheek and wincing at the bruise that was beginning to form.

Abruptly, he straightened and ran his hands over his body and took a few stumbling steps.

"What the hell," he muttered before looking up to find himself on one of the streets of San Fransokyo.

The city sprawled out in front of him, lights forming odd patterns. The occasional hum of a motor broke the silence and the air was warmer than it should have been for January. There were no gashes and empty spaces where there were once buildings and there were too few balloons, wind sensors, in the sky. This was not the city he remembered.

"Wha," he muttered and immediately, his hands flew to feel at his throat.  
There were no lacerations, no bruises, nothing that would have damaged his voice, yet his voice was higher than it should have been, with a faint crack in it.

"Oh my god," he said and the voice of his 14 year old self sounded in his ears. "I’m fourteen again. I’m _fourteen_ again!"

He looked around and up, at the sensors that were lesser in number and were still wind sensors.

"It was the rift, wasn’t it," he said to no one in particular before running through the streets and turning sharply around corners until he crashed to a stop in front of their home.

He bent over, hands on his knees and tried to suck in air through lungs that felt like they were about to collapse.

He looked up as the bell above the door jingled and found himself looking into Tadashi’s face.

"Hiro," his brother asked, confused and Hiro dove at him, wrapping his arms around him and squeezing tightly.

"You’re alive," he mumbled and tried to breathe through the weight that had suddenly appeared in his chest.

"You’re _alive_."


	2. 1

**San Fransokyo, 1 year later, 10: 30 a.m.**

Hiro sighed and pushed himself away from the desk, coughing as he did so. His lungs felt like they were going to burst and as he bent over and coughed into his hand, he could swear he felt blood on his palm.

He looked up from the floor when he heard the familiar sound of vinyl attempting to squeeze through the door frame. His brother's robot, Baymax, squeezed its way through and looked around the room. Upon seeing Hiro, he waved.

"Hello," he said, "I am Baymax. Your personal healthcare companion."

Hiro blinked, confused and got up from his chair, wobbing a little, to approach the marshmallow-like robot.

"What are you doing here?"

"I heard a sound of distress," Baymax said. "I will scan you now."

He nodded his head up and down.

"Scan complete."

Hiro sighed and hurried to shut the door, swaying slightly as he did so, before Baymax could say anything.

"You are dying," Baymax said after a long pause. "Do you wish for me to reveal the information?"

"No!"

Hiro, belatedly, thanked the gods that his lab was soundproof and that Tadashi had programmed Baymax with an understanding of patient confidentiality after Baymax had revealed Aunt Cass’ weight gain and she had lectured Tadashi for several hours.

Hiro frowned. That had been one of the few times they had spoken to each other like brothers after…

He shook his head and once he had turned back to Baymax, the robot began speaking.

"You are aging faster than you should be," the robot said, sounding bewildered.

"Yeah," Hiro laughed, "I fell through a rift in space and time."

That was the only way he could explain having found himself in the San Fransokyo of seven years ago.

Baymax tilted his head and managed to look confused even with his customary expression.

"Long story," Hiro said. "You don’t have to tell me what’s wrong with me. I already know. What are you doing here, in Krei’s labs anyway?"

"He’s with me," Tadashi said, stepping into the room as the door behind him slid out of the way completely and Hiro jumped a little before quickly regaining his footing.

Luckily, Tadashi didn't seem to have noticed, instead looking around the lab, taking in the paper covered walls and metal-part covered desk. Similarily, the floor was covered in scattered metal parts, and he tip-toed over them to reach Baymax’s side.

They stayed in silence for a few moments watching Baymax pick up and examine a large propeller that was on the right edge of the desk.

"Watch the edges," Hiro warned him, "it’s sharp."

"I will be careful," Baymax replied and Hiro nodded before turning back to his brother.

He hadn’t seen his brother properly in almost a year, not since he had sold Krei the microbots in exchange for lab space and materials.

Tadashi appeared to be well, if not tired and a little stressed. It was the way he always looked when they had passed each other on the stairs in tense silence, before Hiro began spending more and more time in his lab.

"You don’t even come home anymore," Tadashi said quietly, looking at him.

He frowned and took a step closer.

"When was the last time you showered?"

"This morning," Hiro snapped and sighed upon seeing the look on Tadashi’s face.

"Sorry," he muttered, looking away and picking up a small, metal disk the size of his palm.

"So," Tadashi said awkwardly, drawing the o out. "What are you working on?"

He stepped closer to get a look at the diagrams on the left corner of the desk and frowned. The diagrams were drawn neatly and everything was documented in clear, blocky handwriting. It was nothing like the handwriting he had seen on Hiro’s notes at home.

"It’s a wind sensor diagram, "Hiro said nonchalantly and launched into an explanation of how it worked.

Tadashi listened, nodding at the appropriate points. It made sense and went along with what the diagrams had told him, but there was still something off and he couldn’t figure out what.

"That’s great," he said, mustering a smile when Hiro finished his explanation.

”So,” Hiro said, leaning forward. “What’re you doing here.”

And it was Tadashi’s turn to explain.

"Professor Callaghan suggested it," he said and nodded at Hiro’s look of surprise.

"I know. I was pretty surprised too, but I guess Callaghan warmed up to him after he got his daughter back."

"Yeah," Hiro agreed with a far-away look on his face.

Tadashi filed it away for later analysis. It wasn't strange to see it now on Hiro's face and it had been a common sight, back when Hiro had still been at home.

"I’ve worked out most of the kinks in Baymax’s programming and he’s been volunteering at one of the local hospitals to get more experience.and Professor Callaghan thought it was time that Baymax went into mass-production. I agreed."

"So," Hiro said slowly, as if trying to work out a particularly complex puzzle. "You’re hoping Krei will agree to produce them."

Tadashi nodded. “Yeah, I just got out of a meeting with him when Baymax wandered off.”

"I heard a sound of distress," Baymax chimed in helpfully, observing them from near the doorway, where he was poking at one of the test blimps that Hiro had in the lab.

"I dropped a wrench on my foot," Hiro lied when Tadashi looked at him with concern. "I’m fine."

Luckily, Baymax didn’t say anything and Tadashi’s expression lightened.

"Be more careful knucklehead."

Hiro grinned, momentarily forgetting about his problems. His brother hadn’t called him that in a while. Things were looking up.

**The Lucky Cat Cafe, San Fransokyo, noon**

"And then Baymax kept insisting that Hiro was his patient," Tadashi finished, popping a chip into his mouth.

His friends stared at him as he ate another two chips. They leaned in, eyes wide.

They were in one of the far corners of the cafe, near one of the windows and close to the pastry display. The plate of chips in front of them was slowly emptying as Tadashi absently ate them as he told them what happened this morning.

"You just left him there," Wasabi asked, incredulous.

Tadashi shrugged and ate a couple more chips.

"What was I supposed to do?" he asked. "Baymax refused to move and Hiro didn't seem to mind having him around."

"Callaghan's not going to be happy about that," Gogo said and swiped a chip, popping it into her mouth and chewing thoughtfully.

"Hey," Tadashi protested and Gogo gave him a glare in response.

"Leave some for the rest of us," she snapped and Tadashi blinked at the plate, surprised.

The plate was nearly empty, with only a few chips and crumbs remaining.

"Sorry," Tadashi said, picking up another chip.

Gogo sighed and shook her head, taking a few more chips as she did so.

Fred frowned and tapped the table with his fingers.

"Hey dude," he said, "what did Baymax mean by your bro being his patient?"

Tadashi put the remainder of his chip down and leaned back in his chair.

"I'm not sure," he said, quietly. "Hiro said he stubbed his toe, but Baymax wouldn't have stuck around if it was just that."

He sighed and ate the last of the chips.

"It must be some quirk in his programming that I have to work out. Hiro looked fine."

Even as he said so, Tadashi made a mental note to go check up on Hiro and Baymax the next day.

**Hiro's lab, San Fransokyo 3:35 p.m.**

Hiro and Baymax spent most of the day in silence. Hiro working on his diagrams and Baymax wandering around the room poking and prodding at various sharp things.

Hiro made sure to keep the tape close by, remembering the incident at the police station where Baymax had taped up the punctures in his body. Luckily, Baymax was careful this time and the tape didn't have to be used.

Eventually, sometime around 2 p.m., Baymax grew restless and wandered off into the hallway. Hiro had jolted out of his trance by the sound of the door sliding shut and blinked when he found that there was no one in the lab except him. He shrugged before turning back to his work. Baymax would be fine, especially if he had been helping out in the hospitals like Tadashi had said.

So, he continued working until the door slid open again and the smell of food wafted through the room.

"You have not eaten," Baymax said as he entered the room, carrying a tray of food in his hands.

Hiro blinked and checked the clock above his desk. It was past 3:30 and all of a sudden, he became aware of the grumbling of his stomach.

"Thanks Baymax," he said gratefully as he pushed aside papers and parts before taking the tray and setting it on the table.

Baymax gave him a nod and started to poke at the balloons by the door again. Hiro laughed before turning to the container and peeling back the foil to find steaming vegetable rice.

He picked up the fork and started to eat, drawing one of the diagrams closer to him and scribbling notes as he did so.

The silence stretched out, broken only by Hiro's chewing, scribbling and Baymax's squeaking as he moved around the lab, examining everything within it.

"You have not slept," he said after a few minutes. "My sensors indicate that your neurotransmitter levels are low; you have not slept for several days."

Hiro sighed, looked up from the diagram he was perusing and rubbed at his eyes.

"I'm very busy," he said. "I don't have time."

" You are lying."

"I-," Hiro started and trailed off with a laugh. "I forgot how good you were at that."

Baymax tilted his head, confused.

"Never mind," Hiro said, shaking his head as he cleaned up his desk.

Some time in the past hour or so, he had finished all of the food without noticing.

When he got to his feet, picking up the tray from the desk, he swayed and Baymax steadied him with an arm.

"You should sleep."

Hiro yawned and gave the tray to Baymax, rubbing his eyes as he did so.

"I guess," he said, shrugging as he moved over to one of the walls and pressed a panel.

The wall opened and out slid a small cot, with no blanket. Baymax tilted his head and looked at it, curious.

"You are not going to go home?"

Hiro flopped on the cot and stared up at him.

"Nope," he said, popping the p and when Baymax didn't immediately untilt his head, sighed and closed his eyes.

"It's complicated, okay," he said and pushed himself upright to look around the lab. "Tadashi didn't leave your charging station?"

Baymax shook his head with a squeak of vinyl.

Hiro groaned, running a hand through his hair in annoyance.

"Fine," he grumbled, grabbing his hoodie and sticking his arms in the sleeves as he headed for the door.

Baymax followed him, head still tilted. Hiro grabbed his arm as the door slid open and tugged him through the doorway.

"We're going home."

**The Lucky Cat Cafe, San Fransokyo 5:00 p.m**

The windows of the cafe shone brightly as they approached it. There were a few customers inside, sipping from cups and talking amongst themselves.

Hiro slowed to a stop in front of the door, Baymax bumping into him.

"You are distressed," he stated after a few moments.

Hiro swallowed and shuffled his feet.

"I haven't been home in a while, so..." He trailed off, looking down at his feet.

There was silence between them for a few moments before Baymax moved forward with a squeak and opened the door.

"What are you doing?" Hiro yelped, following him into the cafe.

"My charger is upstairs."

Baymax headed for the stairs as the rest of the cafe merely gave them brief glances before turning back to their tables, until the sound of a shattering mug made them all glance up and towards the counter.

" _Hiro_ ," his aunt shrieked and he winced, but stood his ground as she jumped over the counter to sweep him up in a squeezing hug.

"Hi Aunt Cass," he said, voice muffled.

His aunt released him, only to whack him lightly on the head.

"Where have you been, young man? It's been two weeks and I haven't seen you once! Do you know how worried I was?"

She continued in the same vein, rambling about how thin he was and then going to bemoan how terrible of a parent she was.

Hiro tuned her out, instead taking in her appearance. She looked well, if not a little more chubby, but that was infinitely better than how she had looked before, when the radiation had enveloped the city after the government had decided to drop a bomb on it in hopes of sealing the rift and when that didn't work, decided to detonate the bomb on the other side of the rift.

"Hiro?" Aunt Cass asked gently, snapping him out of his thoughts. "What's wrong?"

He blinked and blinked again when he felt the wetness in his eyes and laughed nervously as he scratched his head.

"I'm just tired, I guess," he said and when Aunt Cass turned to open the counter, swiped at his eyes with his free hand.

"Come on," she urged as she tugged him through and pushed him in the direction of the kitchen. "I made hot wings!"

Hiro stopped in the doorway of the kitchen as Aunt Cass moved around, heating up the wings and chattering on about what he had missed in the weeks he'd been away.

Hiro leaned against the frame, moving only once to let Baymax through, and listened to her voice, refamiliarizing himself with the intonation.

He yawned again, the warmth of the kitchen making him feel even more tired than before.

Eventually, the wings were done and Aunt Cass waved him over to the table with a "what're you standing there for? Go sit down!" before she ducked out of the kitchen to call Tadashi down.

Hiro fidgeted, watching as Baymax scanned the wings and pronounced them to be mostly unhealthy, yet slightly nutritious.

"This is not something you should be having every day," he said and Hiro nodded.

"Yeah, but it's Aunt Cass' most popular dish. She makes it a lot."

It was on the menu, had been for months and they would constantly get customers asking about the recipe, although Aunt Cass never gave it out, claiming that it was an old family secret.

The sound of footsteps jolted Hiro from his thoughts and he tensed as Aunt Cass hurried into the kitchen, Tadashi following her at a slower pace.

Aunt Cass looked relieved to see him and Hiro frowned, having the sinking feeling that she hadn't expected him to still be there.

Hiro swallowed, throat feeling tight and gave them a shaky smile.

Behind Aunt Cass, Tadashi frowned, looking between him and Baymax, who was petting Mochi.

"What are you doing here?" he asked, stepping forward.

"Baymax needed his charger," Hiro said and sat back in his chair, tucking his hands underneath his thighs.

All of a sudden, the room felt very cold and at the corner of his eye, the kitchen counter wavered and he had to blink rapidly several times before the wavering stopped.

"You okay," Tadashi questioned as he took the seat across from Hiro.

"Yeah," Hiro yawned. "Just tired."

"My scans show you have not slept in several days," Baymax chimed in helpfully from the doorway before disappearing to chase after Mochi.

Hiro glared after him before a throat clearing made him turn slowly to face a worried and slightly angry Tadashi.

"Days Hiro," he said, in that calm, quiet tone that had always made Hiro quiver and feel very guilty.

Hiro shrugged and tried to laugh it off. "I got distracted. You know how it goes."

He could feel a cough rising in his throat and tried to breathe it away. Tadashi's gaze was burning into him and his fingers curled into the skin of his thighs.

"Hiro," Tadashi said softly and Hiro swallowed, opening his mouth.

"Hot wings!"

Aunt Cass placed a large plate of hot wings between them, before taking a seat next to Hiro and ruffling his hair. Tadashi rolled his eyes and got up to grab them plates from the cabinet next to the fridge.

Hiro could feel himself relax as his fingers uncurled and his shoulders slumped.

"Don't worry about him," Aunt Cass whispered as Tadashi took out the stack of plates. "He's just been worried."

Her eyes crinkled as she tensed, preparing to shift towards him. Abruptly, Hiro was reminded of the way she had looked shortly before her death. He shook his head forcefully, pushing the memory down, until it throbbed somewhere just beneath his heart.

"Hiro?" Aunt Cass inquired and squeaked as he got up from his chair and hugged her tightly.

"I missed you," he mumbled, feeling tears drip down his cheeks and onto her shirt.

Above him, he could sense Aunt Cass and Tadashi exchanging worried glances and having an entire, silent conversation over his head, but at this moment he didn't care. Both of them were alive and safe, and that was all that mattered.


	3. Chapter 2

**2:00 a.m. May 5, 2018 The Lucky Cat Cafe, San Fransokyo**

"He asleep?" Aunt Cass whispered, as Tadashi came down the stairs.

She was sitting at the kitchen table with a large, steaming, green mug in her hands.

He nodded, smelling the chamomile from across the room and walking over to the cabinets to get another mug, before sitting down across from her. She pushed the pot of tea, that was in the center of the table, towards him and Tadashi tightened his hands on the cup. Aunt Cass almost never used the teapot, a lacquered black with a red dragon that she had gotten as a gift from their parents.

"I," she began, seeing his glance. "It felt like it was time."

He dipped his head slightly in agreement, taking the pot and pouring himself a cup.

"He's really changed, hasn't he," she sighed as she took another sip.

Tadashi stared down at the liquid in his and didn't answer.

" _Tadashi_ ," Aunt Cass chastised in an attempt to be stern. "What're you thinking?"

He took a deep sip from his cup, staring into its depths as if it held the answers to all of his questions.

"I shouldn't have taken him to the lab. This is my fault."

"Oh Tadashi, _no_."

She put her cup down and placed her hand over his, smiling slightly.

"He's always been unpredictable. Even _you_ can't predict what he'll do all the time."

"I just..." he sighed, shoulders slumping as he leaned forward on an elbow and rested his forehead in his palm.

"What do we do?"

Just then, there was a sharp short scream that came from upstairs.

Both of them jerked, Aunt Cass upsetting her cup, but ignoring the spill in favor of getting to the stairs. Tadashi stopped briefly to grab the towel that hung on the back of his chair, taking a few half-hearted swipes at the liquid before following her upstairs.

By the time he got upstairs, Aunt Cass was already talking to Hiro, who was attempting to convince her that he was fine.

"It was just a nightmare Aunt Cass. They happen sometimes."

Hiro shot Baymax a threatening glare and Tadashi could tell that the robot was about to interject something.

He shook his head, stepping into the room, and made his way to Aunt Cass' side.

"Sorry," Hiro mumbled, seeing him and realizing he had woken everyone in the house.

Tadashi grinned at him, reaching out to poke his cheek.

"You didn't. I was up working on a project," he said, throwing Aunt Cass a sideways glance that Hiro didn't notice.

Aunt Cass shrugged.

"Mochi woke me up," she explained and hoped Hiro wouldn't notice that Mochi was currently fast asleep near the staircase.

Hiro didn't seem to notice; instead, he was looking at Tadashi with narrowed eyes.

"What project," he asked and Tadashi brightened, moving to sit next to Hiro on the bed.

Aunt Cass joined them, nudging Hiro into the middle so she could sit on the opposite edge.

"I've been working on a human-to-human neural interface. I'm hoping it'll be useful in therapy."

Hiro paled, causing both of them to look at him in concern.

"You're working on drift compatibility?" he said, shakily.

Originally, it was Doctor Lightcove that had created the drift technology. He must have changed the timeline more than he had thought if the technology was being created four years ahead of schedule.

"What's drift compatibility?" Tadashi wondered. "I'm working on a neural interface that I hope will be beneficial in therapy....you know what, you can help me test it! I've been working on it all year and it's ready for testing."

Hiro blinked at him and would have fallen out of bed if it wasn't for Aunt Cass next to him.

"Already!" he yelped.

"Yeah!" Tadashi gave him his best, innocent smile.

Aunt Cass shook her head firmly.

"No one is testing _anything_ without supervision," she insisted, happy to see her boys getting along so well after they had nearly stopped talking to each other for an entire year.

"Yes, Aunt Cass, " they chorused and she nodded, satisfied.

"Good," she said, "do you want to talk about your dream, Hiro?"

Hiro pondered the question for a while. Baymax had always said that it was good to talk about what was bothering him and Hiro had always tried to follow that piece of advice.

"I dreamed that a monster attacked the city," he said slowly and watched his brother struggle not to laugh.

"Go on," Aunt Cass said encouragingly and he glared at Tadashi before continuing.

"You died," he told them, voice cracking on the last word.

The day Aunt Cass died, it was, as always, somber out. Ever since the bomb had been dropped on the city, the sky had always shifted between shades of grey. He couldn't remember the last time he had seen its original shade of blue.

They never got many customers in the cafe anymore as everyone had left or was too sick to leave. Those who stayed worked with the government to keep the Kaiju at bay.

"Oh, honey," Aunt Cass sighed affectionately, tossing an arm around his shoulders and hugging him to her.

"No one is going to die from an attack on the city," she continued soothingly, looking to Tadashi for help.

"Yeah, " Tadashi forced a laugh, trying to lighten the moment. "You've been watching too many monster movies bro."

"Yeah, I guess," Hiro said, smiling faintly back.

They didn't know and if he had his way, they'd never know. He had to finish the network and soon. The rift was already opening.

**The Lucky Cat Cafe, San Fransokyo, 10:00 a.m May 5, 2018**

Tadashi and Hiro stood in the garage, staring at the large machine in front of them.

"Wow," Hiro managed after five minutes of silence. "It's big."

Tadashi would have laughed, but upon seeing Hiro's pale face decided against it.

"You don't have to test it if you don't want to."

Hiro considered it, but he _wanted_ his brother to know.

"No, " he shook his head, stepping closer to the machine and examining it. "I _want_ to do this."

Tadashi nodded, fighting to keep the smirk off his face, and stepped around the machine. He found the power cord and quickly plugged it in.

The machine came to life with an ominous hum and a shower of sparks. Hiro eyed it uncertainly and even Tadashi seemed nervous as he moved around to the screen in the center of the machine.

"Are you sure it's ready to be tested?" Hiro asked, plucking at one of the electrodes that was connected to the circlet hanging next to the screen.

Tadashi nodded, a little too quickly for Hiro's taste, but Baymax's charging station was near the desk so they had backup in case something went wrong.

"Here," Tadashi said, taking the contraption with the electrodes and handing it to Hiro, "stick this on your head."

He helped Hiro put it on, strong fingers adjusting the electrodes so they covered all of his head.

"I'll be right here. Okay?"

He waited for Hiro's nod before turning the machine on.

The machine hummed eerily and the electrodes on Hiro's head began to tingle.

At first, Hiro didn't feel or see anything except the back behind his eyelids. Then, he felt the familiar sensation of a memory rushing towards him and then there was nothing but fire.

**SFIT Showcase, San Fransokyo 8:00 p.m. April 15, 2018**

He was with Tadashi, on the bridge and he was telling him that his fly was down. 

_No_ , his mind screamed, every movement and piece of dialog engraved in his memory.

The memory rolled on, despite his best efforts to stop it. Once the rabbit was being chased, there was no way to stop it except to let events play out.

Still he tried, running towards his brother and grabbing his cardigan. Again, he was shrugged off and he tried to grab at him, but his brother had already run up the stairs and into the building.

The explosion happened shortly afterwards, flames billowing outwards and tossing him back. He could smell his hair burning.

**Noon, May 5, 2018 The Garage, The Lucky Cat Cafe, San Fransokyo**

Someone was screaming, loud and shrill, and there was yowling somewhere in the midst of it all. Something was burning too.

He felt himself stagger as the weight of the contraption on his head lifted and the restraints around his arms slid away. Shaking arms wrapped around him and he trembled as the scent of mint and lemon wafted towards him;his brother's weird shampoo.

He tried to balance himself, but Tadashi's rapid fire questions of "Hiro, what happened, are you okay," didn't allow him to do so and the pounding in his head made the room swirl.

There was the sound of firm and rapid footsteps and the ache in his head intensified as the garage door was flung open and Aunt Cass started yelling at them both.

 **12:30 p.m May 5, 2018 The Lucky Cat Cafe, San Fransokyo**  

Both of them sat on the couch, too afraid to move. They had never seen Aunt Cass that angry, not even when they had gotten arrested after Hiro's bot fight with Yama.

"She's right, you know,"Tadashi said, breaking their silence.

Both Hiro and Mochi looked up from their curled up positions on the couch and nearly toppled over each other as Hiro tried to get to his side. Tadashi laughed, quailing slightly at the sound of Aunt Cass' angry shout.

"I hope Baymax calms her down soon," Hiro murmured, curling into Tadashi's side.

Absently, Tadashi nodded, combing a hand through Hiro's hair and feeling out the slightly singed bits. The other wrapped around Hiro and tugged him closer.

"I thought it was ready," he said quietly.

Hiro shrugged. "You're gonna figure it out bro, don't worry."

Tadashi nodded. The silence stretched out as his thoughts whirled in his mind. He was a terrible big brother; he should have done more tests and had someone other than Hiro test it. There was something else too. The fire at SFIT that he had seen in Hiro's mind.

He remembered that day; it was the showcase. Hiro had stolen the show with his microbots and then....then he had accepted Krei's offer and everything had fallen apart.

Tadashi hugged Hiro tighter and shook his head when Hiro looked at him questioningly.

Of all the things to happen that day, a fire wasn't one of them. So why was it in Hiro's mind?

Before, he could ponder that further, Aunt Cass's entrance jolted him out of his thoughts.

Her hair was sticking up in places, her shirt was wrinkled and it looked like there were tear tracks on her face. Both of them tensed as she walked over, crossing her arms and glaring at them.

Baymax followed her in and headed towards his charging station. He stepped in and deflated, the red box closing over him.

"Baymax does not count as supervision," Aunt Cass asserted sharply, and gestured towards the kitchen, jabbing her thumb behind her head. "I made you lunch. Eat and _stay up here_. You're both banned from the garage until further notice. Got that?"

They nodded. "Yes, Aunt Cass."

She gave them both a wary glance. "Good."

They didn't move until they heard her footsteps fade into the cafe.

"We need to make it up to her," Hiro said, stroking Mochi, who had jumped on his lap.

Tadashi made an agreeing sound. Neither of them moved, their breathing and Mochi's purring mixing together to form a lullaby that nearly sent them to sleep.

Eventually, Tadashi pulled away, ignoring Hiro's protesting whine, and stood up.

"Lunchtime," he said, heading for the kitchen.

Groaning slightly, Hiro got up from the couch, dislodging Mochi-who meowed angrily- and followed.

 **11:00 p.m May 5, 2018 The Lucky Cat Cafe, San Fransokyo**  

Tadashi paced the living room, keeping his footsteps light as both Hiro and Aunt Cass were asleep. The light from the streetlights cast the room into strange shadows and he shook a little; they looked like the flames he had seen in Hiro's not-memory.

He frowned. The scene that he had seen on the screen had been too detailed to have been false, but he _did not_  remember that happening. Come to think of it, that entire night had been weird.

He knew Hiro would be nervous; he never did like public speaking and to have his college acceptance riding on it didn't do him any favors, but he had never seen his brother that nervous.

**SFIT Showcase, San Fransokyo 1:30 p.m. April 15, 2018**

His brother paced around his bins, shaking like the leaves of the trees beside the cafe.

" Relax," Honey said, "you'll do fine!"

"That's what I'm worried about," his brother said under his breath and Tadashi knew that if he wasn't standing right next to Hiro, he'd have never heard it.

He put it aside for later consideration. It probably didn't mean anything. Hiro was just anxious.

The presentation went- he really wasn't sure how to put this. It was what one would expect of a presentation, but the entire thing seemed off in a way he couldn't articulate.

Then Alistair Krei came over and the hairs on the back of his neck rose. There was a calculating glint in his brother's eyes, like the one he got when he was planning on sneaking out to bot fight.

Hiro went still in a way Tadashi had never seen and even their friends noticed, tossing him quick, worried glances.

"...your microbots could help a lot of people," Krei was saying when Tadashi tuned back in.

Both Callaghan and Krei were trying to sway Hiro to their side, but he knew his brother too well to know that neither of them could change his mind.

"Okay," Hiro said and Tadashi felt his breath catch.

He thought he knew his brother, but the Hiro he knew would never have said yes.

"I revoke your acceptance then," Callaghan said, bluntly. "You made the wrong choice, Hiro."

His brother nodded, almost as if he was expecting this, and Krei slung an arm around his shoulders and steered him away.

"Let's talk, shall we?"

Hiro let him and Tadashi's heart dropped to his stomach. He was so sure his brother would have joined him at SFIT and stayed out of trouble, but Hiro seemed intent on finding trouble and he didn't know what to do anymore.

**11:10 p.m May 5, 2018 The Lucky Cat Cafe, San Fransokyo**

Roughly, Tadashi shook himself out of the memory. He didn't want to remember their argument. Even now, thinking about it made his chest hurt and he had to several deep breaths to try and get the feeling to lift.

Sighing, he flopped on the couch and stared at the ceiling. Taking out his phone, he texted their friends.

_Something's up with Hiro and I need your help finding out what. Meet me at the cafe, tomorrow, 9 am._

The entire situation with Hiro made something inside of him quake in fear and he had the strangest feeling that time was running out.

**Author's Note:**

> Please tell me what you think of it, thanks. 
> 
> By the way, if anyone's curious, there is author speak on the fic [here](http://writingfish.tumblr.com/tagged/writing-rim-of-the-past), including fic planning.


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